Nibbling tool

ABSTRACT

A hand-operated nibbling tool for use with sheet material is provided with an elongated frame and with a pistol-type hand grip at its rear end and a downwardly depending trigger-like operating lever forwardly of the hand grip. The operating lever has camming engagement with an elongated punch lever pivoted at one end on the frame adjacent the hand grip and having a punch at its other end which, in cooperation with a die formed in the frame adjacent its forward end, operates to shear consecutive small rectangular pieces from the sheet material. The location of the pivots and the shape of the camming surface are such as to provide ease of operation and also a varying operating speed, if desired.

United States Patent [1 1 Hunt [ Nov. 28, 1973 NIBBLING TOOL [75] Inventor: Guilbert M. Hunt, Brecksville, Ohio [73] Assignee: The Stanley Works, New Britain,

Conn.

221 Filed: Feb. 16,1972

211 App]. No.: 226,682

Primary Examiner- Othell M. Simpson Assistant Examiner-Harold P. Smith, Jr. Attorney-John M. Prutzman et al.

[5 7] ABSTRACT A hand-operated nibbling tool for use with sheet material is provided with an elongated frame and with a pistol-type hand grip at its rear end and a downwardly depending trigger-like operating lever forwardly of the hand grip. The operating lever has camming engagement with an elongated punch lever pivoted at one end on the frame adjacent the hand grip and having a punch at its other end which, in cooperation with a die formed in the frame adjacent its forward end, operates to shear consecutive small rectangular pieces from the sheet material. The location of the pivots and the shape of the camming surface are such as to provide ease of operation and also a varying operating speed,

if desired.

9 Claims, 7 Drawing Figures PAIENIEDnuvao ms sum 10E 2 NIBBLING TOOL BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to nibbling tools of the type which have a punch and die for removing consecutive small segments from sheet material enabling the operator, for example, to form thin slots, either straight or curved, in the sheet material, or to cut openings of substantially any size or shape therein, or to contour the edge thereof.

An object of the present invention is to provide a hand-operated nibbling tool which has the capacity for cutting a variety of commonly used sheet materials such as metal sheets, hard surface laminates, vinyl asbestos'floor tile, vinyl siding, cardboard and the like and yet is of compact design and easy to operate without undue strain.

A further object is to provide such a tool which is convenient to use from the standpoint of easy application to the workpiece as well as good visibility of the location ahd progress of the cutting action, and minimum interference between the tool and workpiece by way of binding or wedging particularly when making extended cuts and turns.

Another object of the invention is to provide a nib bling tool having an improved cutting action to permit repeated removal of small segments of the sheet material with the application of minimum pressure, and which provides clean cuts without distortion of the workpiece or forming burrs.

An additional object is to provide a nibbling tool of simple design and yet rugged so as to have a long service life and which can be readily disassembled for resharpening or replacing the punch.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

A better understanding of the invention will be obtained from the following detailed description and accompanying drawings illustrating a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. '1 is a perspective view of an assembled tool embodying theinvention together with a fragmentary workpiece;

FIG. 2 is an enlarged partial side view thereof, partly in cross section;

FIG. 3 is a partial cross-sectional view taken along the line of 3-3 of FIG. 2;

FIG. 4 is a partial side view of the punch and die assembly of the tool;

FIG. 5 is a partial cross-sectional view taken along the line of 55 of FIG. 4;

FIG. 6 is a partial cross-sectional view taken along the line of 6-6 of FIG. 4; and

FIG. 7 is a partial cross-sectional view corresponding to a portion of FIG. 2 but showing the operating parts in fully actuated position.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings in detail, a preferred embodiment of a hand-operated nibbling tool of the present invention is shown as having an elongated channelshaped frame member 10. As more particularly described hereinafter, the upper surface of the frame member 10 forms an anvil or supporting surface for the workpiece to be operated upon by the tool and the forward end is provided with a rectangular opening 11 forming a die. The forward edge 12 of the opening 11 is slightly inclined rearwardly to accommodate the slight arcuate movement of the punch as described more particularly hereinafter. The frame member is preferably formed of carbon steel which can be heat treated particularly in the area surrounding the opening 7 11 so as to provide a hard shearing surface.

Clamped to opposite sides of the frame member 10 and to each other are handle members 14 preferably formed of molded plastic. The edges of the handle members 14 are contoured to fit around and enclose the sides and ends of the frame member 10 and have mating flanges 15 enclosing the bottom of the tool. The handle members 141 are clamped to the frame 10 and to each other by means of posts 16 which have internally threaded openings for receiving the screws 17. The flanges 15 form a pocket below the opening 11 for receiving chips severed from the workpiece and these may be removed through the forward opening 18 formed in the handle members 14 at the'forward end of the tool.

Cooperating with frame member 10 and the die provided by the opening 11 is an elongated lever 20 pivotally mounted on the rear end of the frame member 10 by the fastening post 16 secured therethrough. The forward end of the lever 20 is provided with an upwardly extending angularly related shank portion 21 terminating in a forwardly extending punch 22 configured to cooperate with the forward edges of the die opening 11. In order to provide easy cutting, particularly of sheet metal, with minimum resistance, the lower work engaging surface 23 of the punch is inclined both transversely and rearwardly of the punch so as to provide a progressive or splay shearing action rather than simultaneous uniform engagement with all edges of the segment to be removed from the workpiece. The sides 24 of the punch are slightly tapered inwardly toward the top of the punch for clearance purposes. It also will be noted that the side surfaces 25 of the shank also are inclined or tapered toward the rear to provide clearance with the edges of the workpiece to permit turning of the tool relative to the workpiece as required when making cuts other than in a straight line and permitting such cuts to be made on a small radius, if desired.

Inasmuch as the punch 22 is mounted on a pivoted lever 20, its path of movement is arcuate but because of the relatively long length of the lever 20, the path of movement relative to the edge 12 of the die is nearly rectilinear and is easily accommodated by slightly undercutting the edge 12 as previously mentioned. Also, it will be noted, the front face 26 of punch 22 is inclined rearwardly for clearance purposes. Because the pivot for the lever 20 is precisely fixed, the desired tolerance between the punch and edge 12 is easily maintained. Also, the maximum width of the shank 21 is the same as that of the punch 22 and acts as guide accurately positioning the punch 22 laterally for precise cooperation with the side edges of the die.

Pivotally mounted on the frame 10 by means of a pivot pin 30 is a trigger lever 31 which depends downwardly from the frame, forwardly of the pistol grip portion 19 of the handle members 14 whereby the lever 31 may be readily actuated by the fingers of the operator holding the pistol grip portion in the palm of his hand.

The trigger lever 31 is conveniently made of sheet material which is of tapered channel shape and which has inwardly inset tangs 32 adapted to be received within the frame member and extending on opposite side of the punch lever 20. A bumper 33 of resilient material is provided to prevent pinching of the operators hand when the tool is actuated.

As best shown in FIGS. 2 and 7 of the drawings, the upper edge of the punch lever 20 adjacent the shank 21 is formed with a contoured cam surface 40 which cooperates with a roller cam 41 on the trigger lever 31. A leaf spring 42 mounted in a slot 43 formed in the shoulders 44 of the handle members 14 bears against the underside of the lever 20 to operate as a return spring urging the parts to the position shown in FIG. 2. The cam surface 40 is so shaped and the location of the pivots is such that when the trigger lever 31 is actuated rearwardly by the operator, the punch 22 is given a rapid downward movement at the beginning of the stroke, a slower movement near the center of the stroke and a rapid movement at the end of the stroke. The advantage of this varying speed of movement of the punch 22 is that at the beginning of the movement, the die would not be in contact with a thin workpiece such as sheet metals, but in the case of thicker materials such as floor tile, there would be engagement but the resistance would be only moderate. The slower movement of the punch near the center of the stroke with its accompanying greater mechanical advantage provides the maximum punch pressure required for cutting sheet metals. The rapid movement of the punch at the end of the stroke aids in completely shearing through the material being cut.

In the operation of the tool, a workpiece such as workpiece 50 shown in FIG. 1 is placed on the upper surface of the frame member 10 so that it will be engaged by the punch 22 when the tool is actuated. Upon actuation ofthe punch by squeezing the trigger lever 31 toward the pistol grip 19, a small rectangular piece is engaged by the under surface 23 of the punch and completely severed from the workpiece by the shearing action of the edges of the punch in cooperation with the die 11. This can be repeated at a rapid rate as the workpiece is advanced to form an inwardly extending cut such as shown in the workpiece 50.

A hold-down and alignment screw 51 may be provided to assist in positioning the workpiece and particularly to guide the tool when making straight cuts. The hold-down screw 51 may be threadably mounted in the rear of the frame as shown in FIG. 1 or alternatively may be positioned forwardly in the threaded opening 52, the rearward provision providing a more accurate guide for long straight cuts. The shank of the holddown screw 51 is approximately the same size as the transverse dimension of the punch 22 so that it will fit in the slot cut in the workpiece and it has a wing portion 53 which overlies the side edges of the cutting portion thus holding the sheet material against the top surface of the frame member 10. Because of the inward taper of the side edges 25 of the shank 21 from which the punch 22 projects, the tool and workpiece may be turned relative to each other without binding, thus permitting successive angularly related cuts to be made and also permits cutting curved slots of small radii. Inasmuch as a complete segment is cut out on each stroke, it is possible to cut notches or openings in the workpiece of any shape desired. When making angularly related cuts, of course, the hold-down screw is removed. The disposition of the pistol grip 19 and trigger lever 31 is such that they provide no interference with the movement of the workpiece relative to the tool and the operation and location of the tool relative to the workpiece is fully exposed and visible at all times, permitting easy and accurate cutting of even intricate shapes.

The mechanical advantage provided by the punch and die assembly and trigger action of the present invention using the elongated punch lever 20 and the varying cam action provides a tool having great versatility and usefulness in a small size. For example, a tool can be constructed in accordance with the present invention with a length not exceeding about five inches and yet which will easily cut soft steel sheets up to a thickness of 0.35 inch or aluminum sheets up to 0.050 inch thick and non-metal sheets up to one-eighth inch thickness. The design of the punch and die assembly assures accurate positioning and movement of the punch relative to the die so that close tolerances are possible and, also, as will be apparent, the tool can be easily disassembled for sharpening or replacement of the punch.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

I claim:

1. A hand-operated nibbling tool comprising an elongated frame, a die formed adjacent one end of the frame, an elongated lever having one end pivotally mounted adjacent the end of the frame opposite said one end, a punch on the free end of the elongated lever configured to cooperate with said die, an operating lever pivotally mounted on the frame between the die and the pivot of the elongated lever, and means on the operating lever engaging the elongated lever to pivot the elongated lever when the operating lever is pivoted and actuate the punch relative to the die.

2. The nibbling tool of claim 1 wherein the frame is a downwardly opening channel member having an upper surface for supporting a sheet material, the die is an opening in the frame, and the elongated lever is pivotally mounted within the channel member and has a shank supporting the punch for movement relative to the die.

3. The nibbling tool of claim 2 wherein the punch projects forwardly from the shank of the elongated lever and has front and side edges disposed in close proximity to the front and side edges of the die when the punch is positioned at the die opening.

4. The nibbling tool of claim 3 wherein the bottom surface of the punch defined by the said front and side edges of the punch is inclined laterally and rearwardly of the punch.

5. The nibbling tool of claim 3 wherein the shank of the elongated lever is substantially the same width as the front edge of the punch and by extension through the die aligns the punch with the die.

6. The nibbling tool of claim 1 wherein the means on the operating lever engaging the elongated lever is a cam engaging a camming surface on the elongated lever, and wherein the location of the pivots and the shape of the camming surface is such as to provide slower movement of the punch adjacent the entrance of the die than at the beginning and end of the stroke.

lever, and the operating lever carries a cam engaging an upper camming surface on the elongated lever adjacent the shank thereof.

9. The nibbling tool of claim 2 wherein a winged hold-down and guide screw is threadably mounted on the frame extending upwardly from the upper surface thereof rearwardly of and in alignment with the punch. =l 

1. A hand-operated nibbling tool comprising an elongated frame, a die formed adjacent one end of the frame, an elongated lever having one end pivotally mounted adjacent the end of the frame opposite said one end, a punch on the free end of the elongated lever configured to cooperate with said die, an operating lever pivotally mounted on the frame between the die and the pivot of the elongated lever, and means on the operating lever engaging the elongated lever to pivot the elongated lever when the operating lever is pivoted and actuate the punch relative to the die.
 2. The nibbling tool of claim 1 wherein the frame is a downwardly opening channel member having an upper surface for supporting a sheet material, the die is an opening in the frame, and the elongated lever is pivotally mounted within the channel member and has a shank supporting the punch for movement relative to the die.
 3. The nibbling tool of claim 2 wherein the punch projects forwardly from the shank of the elongated lever and has front and side edges disposed in close proximity to the front and side edges of the die when the punch is positioned at the die opening.
 4. The nibbling tool of claim 3 wherein the bottom surface of the punch defined by the said front and side edges of the punch is inclined laterally and rearwardly of the punch.
 5. The nibbling tool of claim 3 wherein the shank of the elongated lever is substantially the same width as the front edge of the punch and by extension through the die aligns the punch with the die.
 6. The nibbling tool of claim 1 wherein the means on the operating lever engaging the elongated lever is a cam engaging a camming surface on the elongated lever, and wherein the location of the pivots and the shape of the camming surface is such as to provide slower movement of the punch adjacent the entrance of the die than at the beginning and end of the stroke.
 7. The nibbling tool of claim 2 wherein a pistol grip handle is fixed to and depends downwardly from the frame adjacent the pivoted end of the elongated lever and the operating lever is in the form of a trigger depending downwardly from the frame forwardly of the pistol grip.
 8. The nibbling tool of claim 7 wherein the pivot for the operating lever is positioned above the elongated lever, and the operating lever carries a cam engaging an upper camming surface on the elongated lever adjacent the shank thereof.
 9. The nibbling tool of claim 2 wherein a winged hold-down and guide screw is threadably mounted on the frame extending upwardly from the upper surface thereof rearwardly of and in alignment with the punch. 